DESCRIPTION: The application describes previous studies in which systemic priming of rhesus macaques with formalin-inactivated whole SIV in microspheres, followed by oral or intratracheal boosting with the microencapsulated vaccine, resulted in significant protection against intravaginal challenge with live pathogenic SIV. The application also describes various proposed approaches to improve upon mucosal immunization including: (1) utilizing recombinant vaccinia virus expression systems for the production of non-infectious virus-like particles (VLP's) to be used as antigens in microencapsulated vaccines, (2) developing recombinant baculovirus expression systems for expression of SIV and HIV virus-like particles, and (3) developing approaches for mucosal immunization with non-replicating plasmids encoding HIV and SIV antigens. (Adapted from the Application).